#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>

int Fac(int n)
{
	int a = 1, b = 1, c = 1;
	while (n)
	{
		if (n > 2)
		{
			c = a + b;
			a = b;
			b = c;
		}
		n--;
	}
	return c;
}



int main()
{
	int n = 0;
	while (scanf("%d", &n))
	{
		int ret = Fac(n);
		printf("%d", ret);
	}
	return 0;
}